1. Field of the Invention
This invention disclosure relates to the processing of seismic data, and, in particular, to a technique for performing a fast residual migration of seismic data through parsimonious image decomposition.
2. Discussion of Related Art
This section of this document is intended to introduce various aspects of the art that may be related to various aspects of the present invention described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the present invention. As the section's title implies, this is a discussion of related art. That such art is related in no way implies that it is also prior art. The related art may or may not be prior art. It should therefore be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Seismic exploration involves surveying subterranean geological formations for hydrocarbon deposits. A survey typically involves deploying acoustic source(s) and acoustic sensors at predetermined locations. The sources impart acoustic waves into the geological formations. The acoustic waves are sometime also referred to as “pressure waves” because of the way they propagate. Features of the geological formation reflect the pressure waves to the sensors. The sensors receive the reflected waves, which are detected, conditioned, and processed to generate seismic data. Analysis of the seismic data can then indicate the presence or absence of probable locations of hydrocarbon deposits.
Once acquired, the recorded seismic data is generally processed to facilitate its end use. A number of techniques are employed depending on the analysis that is to be performed. One such technique is called “fast migration”. Many techniques for fast migration using beam decompositions are known to the art. In such a migration, conventional practice often discards many of the beams so to rapidly image important features in the input dataset. It is advantageous to have a “parsimonious” transformation that represents a large amount of the energy in the data with a few coefficients.
Beam formation can be posed as prestack data decompositions in the shot-receiver domains or common offset domain. Or, beam formation can be posed as post migration decompositions in offset or angle domains. These methods are also related to older methods such as Gaussian beam migration.
The goal of the beam decomposition is to represent the data in a more parsimonious form so that the data can be depth migrated more efficiently. Since migration is a process that varies with position and dip it is natural to consider decompositions that have the property of being local in space and dip.
Data migration often uses a ray based method to reposition the energy from the input beams to their final imaged position. The takeoff angles for the rays are given by the dip (or dips) associated with each beam. The position in the final image is strongly dependent on the dip identified in the data. This means that making an accurate estimate of the dip is an important part of the process. In particular it is undesirable to have only a limed number of fixed dips (e.g. equally sampled dips in a range). The goal should be to get the best possible dip estimate from the continuous range of dips.
References directed to these matters include:    Ling Chen, et al., “Target-Oriented Beamlet Migration Based on Gabor-Daubechies Frame Decomposition”, 71 Geophysics S37 (2006);    U.S. Patent Publication 2006/0056272, entitled “Methods for Earth Modeling and Seismic Imaging Using Interactive and Selective Updating”, filed Sep. 13, 2004, in the name of the inventor N. Ross Hill;    “Applied Geophysical Services”, downloaded Dec. 20, 2007, from http://www.appliedgeo.com/services.html;    U.S. Patent Publication 2007/0271041, entitled “Diplet-Based Seismic Processing”, filed May 17, 2007, in the name of the inventor Chengbin Peng;    U.S. Provisional Patent Application 60/801,133, entitled “3D Diplet Demigration and Remigration”, filed May 17, 2006, in the name of the inventor Chengbin Peng;    Huub Douma, et al., “Wave-character Perserving Pre-Stack Map Migration Using Curvelets”, SEG Int'l Exposition and 74 Annual Meeting (Oct. 10-15, 2004);    “CGGVeritas Fast Beam Migration”, downloaded Dec. 20, 2007, from http://www0.cgg.com/proserv/processing/Services/FBM/Speed.html;    Fuchun Gao, et al., “Fast Beam Migration—A Step Toward Interactive Imaging”, SEG 2006 Annual Meeting;    F. Rocca, “Residual Migration”;    Biaolong Hua, et al., “Parsimonious 2D prestack Kirchoff Depth Migration”, 68 Geophysics 1043 (2003);    Karel Zacek, “Gaussian Packet Pre-Stack Depth Migration”, SEG Int'l Exposition and 74th Annual Meeting (Oct. 10-15, 2004); and    Frank Adler, “Kirchoff Image Propagation”, 67 Geophysics 126 (2002).
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.